scholarly journals An EMI-Based Clustering for Structural Health Monitoring of NSM FRP Strengthening Systems

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3775 ◽  
Author(s):  
Ricardo Perera ◽  
Lluis Torres ◽  
Antonio Ruiz ◽  
Cristina Barris ◽  
Marta Baena
Keyword(s):  
Failure Modes ◽  
Damage Identification ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Complex Problem ◽  
Concrete Cover ◽  
Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Near Surface ◽  
Electromechanical Impedance

The use of fiber-reinforced polymers (FRP) in civil construction applications with the near-surface mounted (NSM) method has gained considerable popularity worldwide and can produce confident strengthening and repairing systems for existing concrete structures. By using this technique, the FRP reinforcement is installed into slits cut into the concrete cover using cement mortar or epoxy as bonding materials, yielding an attractive method to strengthen concrete structures as an advantageous alternative to the external bonding of FRP sheets. However, in addition to the two conventional failure modes of concrete beams, sudden and brittle debonding failures are still likely to happen. Due to this, a damage identification technology able to identify anomalies at early stages is needed. In this work, some relevant cluster-based methods and their adaptation to electromechanical impedance (EMI)-based damage detection in NSM-FRP strengthened structures are developed and validated with experimental tests. The performance of the proposed clustering approaches and their evaluation in comparison with the experimental observations have shown a strong potential of these techniques as damage identification methodology in an especially complex problem such as NSM-FRP strengthened concrete structures.

scholarly journals Inclusion of CFRP-Epoxy Composite for End Anchorage in NSM-Epoxy Strengthened Beams

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Md. Akter Hosen ◽  
Mohd Zamin Jumaat ◽  
A. B. M. Saiful Islam
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Concrete Cover ◽  
Structural Members ◽  
Premature Failure ◽  
Near Surface ◽  
Steel Bars ◽  
Near Surface Mounted ◽  
Separation Failure ◽  
Concrete Cover Separation

Nowadays, the use of near surface mounted (NSM) technique strengthening reinforced concrete (RC) structural members is going very popular. The failure modes of NSM strengthened reinforced concrete (RC) beams have been shown to be largely due to premature failure such as concrete cover separation. In this study, CFRP U-wrap end anchorage with CFRP fabrics was used to eliminate the concrete cover separation failure. A total of eight RC rectangular beam specimens of 125 mm width, 250 mm depth, and 2300 mm length were tested. One specimen was kept unstrengthened as a reference; three specimens were strengthened with NSM steel bars and the remaining four specimens were strengthened with NSM steel bars together with the U-wrap end anchorage. The experimental results showed that wrapped strengthened beams had higher flexural strength and superior ductility performance. The results also show that these beams had less deflection, strain, crack width, and spacing.

scholarly journals Evaluation of Concrete Structures Reinforced with Fiber Reinforced Polymers Bars: A Review

2017 ◽  
Vol 7 (5) ◽  
pp. 165-175 ◽  
Author(s):  
Masoud Abedini ◽  
Ebrahim Akhlaghi ◽  
Javad Mehrmashhadi ◽  
Mohamed H Mussa ◽  
Mohammad Ansari ◽  
...  
Keyword(s):  
Concrete Structures ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers

scholarly journals Durability Issues and Corrosion of Structural Materials and Systems in Farm Environment

2020 ◽  
Vol 10 (3) ◽  
pp. 990 ◽  
Author(s):  
Chrysanthos Maraveas
Keyword(s):  
Concrete Structures ◽  
Animal Manure ◽  
Fiber Reinforced Polymers ◽  
Pig Manure ◽  
Exposure Limits ◽  
Viable Option ◽  
Reinforced Polymers ◽  
Metal Structures ◽  
Farm Structures ◽  
Materials Used

This review paper investigated the durability and corrosion of materials used in the construction of agricultural buildings. Even though concrete and metal were the materials of choice in the construction of farm structures, they are susceptible to corrosion and environmental degradation. Acid attacks result in the oxidation of metals and mass losses and reduced compressive strength of the metal structures. Concrete structures are degraded in high humidity environments, such as lagoons, agricultural effluents, and animal manure. Poultry, cow, and pig manure contain variable quantities of corrosion-inducing chemicals, such as sulfates, nitrates, chlorides, hydrogen sulfide, and ammonia. However, the degradation of concrete structures can be mitigated by the utilization of modified concrete containing sulfur, fly ash, silica fume, and nanoparticles such as silica. Concrete structures made of fiber-reinforced polymers are less prone to corrosion and are more durable. The design for durability has also emerged as a viable option for optimizing the service life of agricultural buildings by adhering to the exposure limits.

scholarly journals FRP REINFORCEMENT FOR CONCRETE STRUCTURES: STATE-OF-THE-ART REVIEW OF APPLICATION AND DESIGN

2014 ◽  
Vol 5 (4) ◽  
pp. 147-158 ◽  
Author(s):  
Eugenijus Gudonis ◽  
Edgaras Timinskas ◽  
Viktor Gribniak ◽  
Gintaris Kaklauskas ◽  
Aleksandr K. Arnautov ◽  
...  
Keyword(s):  
Material Properties ◽  
Structural Engineering ◽  
State Of The Art ◽  
Concrete Structures ◽  
Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Promising Alternative ◽  
Frp Composites ◽  
Structural Problems ◽  
Concrete Elements

Fiber reinforced polymers (FRPs) are considered to be a promising alternative to steel reinforcement, especially in concrete structures subjected to an aggressive environment or to the effects of electromagnetic fields. Although attempts to develop effective reinforcement have been followed, the application of FRPs remains limited by the solution to simple structural problems that mainly appear due to the absence of design codes, significant variation in the material properties of FRP composites and limited knowledge gained by engineers as regards the application aspects of FRP composites and structural mechanics of concrete elements reinforced with FRPs. To fill the latter gap, the current state-of-the-art report is dedicated to present recent achievements in FRPs applying practice to a broad engineers’ community. The report also revises the manufacturing process, material properties, the application area and design peculiarities of concrete elements reinforced with FRP composites. Along the focus on internal reinforcement, the paper overviews recent practices of applying FRP reinforced concrete (RC) elements in structural engineering. The review highlights the main problems restricting the application of FRPs in building industry and reveals the problematic issues (related to the material properties of the FRP) important for designing RC following the formulation of targets for further research.

Numerical Interpretation of Bond Between Steel and Concrete in Presence of Corrosion and Cyclic Action

2009 ◽  
Vol 417-418 ◽  
pp. 349-352 ◽  
Author(s):  
Luca Giordano ◽  
Giuseppe Mancini ◽  
Francesco Tondolo
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Stress Transfer ◽  
Experimental Tests ◽  
Radial Pressure ◽  
Mechanical Action ◽  
Concrete Cover ◽  
Reinforcing Bars ◽  
Cyclic Action ◽  
Bond Slip

Bond between steel and concrete in reinforced concrete structures plays a fundamental role. The stress transfer mechanism depends on the condition of the contact surface between the two materials, the mechanical characteristics of concrete near the rebar and on the available level of confinement. Corrosion of reinforcing bars in concrete structures modifies those three factors. Because of corrosion, on the rebar surface a granular oxide layer is present and with its expansion it generates a significant radial pressure; consequently tensile stresses grow till cracking of the concrete cover with a subsequent reduction of the confinement effect. Moreover the presence of a mechanical action modifies the resisting mechanism producing an increasing damage. In this study, a model is presented for the numerical simulation of experimental tests on r.c. ties subjected to mechanical action; furthermore some considerations on reinforced concrete ties subjected also to corrosion effect are reported. From those analyses it is possible to estimate a modified bond-slip law between the reinforcing bars and the concrete, in order to take into account the level of damage.

scholarly journals Reinforced concrete structures strengthened with CFRP (ACI x FIB) - Recommendations for bending design criteria

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Igor Del Gaudio Orlando ◽  
Túlio Nogueira Bittencourt ◽  
Leila Cristina Meneghetti
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Fiber Reinforced Polymers ◽  
Design Criteria ◽  
Ultimate Limit State ◽  
Reinforced Concrete Structures ◽  
Carbon Fiber Reinforced Polymers ◽  
Model Code

abstract: This work deals with the evaluation of the design criteria and security check (Ultimate Limit State - ULS) of the American (ACI-440.2R, 2017) and European (FIB Model Code, 2010) standards of reinforced concrete structures strengthened with Carbon Fiber Reinforced Polymers (CFRP), by the technique of Externally Bonded Reinforcement (EBR). It is intended to evaluate if, for a given database of 64 experimental tests of beams and slabs, the obtained results respect the safety conditions according to the mentioned standards, to increase the efficiency of this reinforcement technique and to lead to the establishment of regulatory design criteria in Brazil. Results show a conservative match among experimental and theoretical values calculated according to the two guidelines and it is concluded that a future regulation in Brazil on this subject should be based on the FIB Model Code.

scholarly journals Investigation of crack prediction in reinforced concrete liquid containing structures

2021 ◽  
Author(s):  
Armin Zyarishalmani
Keyword(s):  
Reinforced Concrete ◽  
Prediction Models ◽  
Theoretical Calculations ◽  
Experimental Tests ◽  
Fiber Reinforced Polymers ◽  
Water Leakage ◽  
Positive Role ◽  
Reinforced Polymers ◽  
Cracking Behavior ◽  
Advantages And Disadvantages

Cracking in liquid containing structures, if it is not properly controlled, can have serious detrimental effects on the overall system functionality. Having a consistent knowledge of concrete cracking characteristics is essential for a designer to ensure serviceability requirements of the structure. In spite of several proposed crack prediction models that have been used as the base for design codes, still a lack of certainty can be clearly felt in predicting cracking behavior of reinforced concrete. This is due to the fact that cracking is a very complex phenomenon in which numerous factors are involved, and it is always too cumbersome to take the effects of all these influential aspects into account. In order to acquire more insight into this issue, a comprehensive attempt has been made both experimentally and theoretically here in this study. This research is primarily dealing with cracks that develop under monotonic increasing load which is the main cause for the formation of wide cracks among other causes such as shrinkage or temperature. In this regard, several laboratory tests were conducted on a one meter wide strip of a tank wall. These experiments covered a range of loading configuration that would enable various combinations of stresses across the reinforced concrete section. Cracking behavior and water tightness of the slab were closely monitored and reported. Fiber reinforced polymers were shown to be a suitable means of remediation in reducing water leakage or recovering structural strength. A positive role of concrete autogenous healing on water leakage was investigated during the practical test. A comparison is made between experimental results and several recent well-known crack prediction models, through which their advantages and disadvantages are revealed and discussed. Several finite element models (FEM) have been successfully built with the aid of computer program ABAQUS/6.5 to capture the post-failure stress/strain condition in concrete and reinforcement, the results of which are perfectly matching with those obtained from experimental tests and theoretical calculations.

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